com.tangosol.net.cache
Class OverflowMap.Status

The Status object is used to manage concurrency at the key level for the key-level operations against the Map, to track all the items in the front Map, to manage the state transition for operations occurring against the Map, and to coordinate events across multiple threads.

OverflowMap.Status

getStatus

Determine the enumerated status of the Status object. This value is intended for internal and debugging use only, and should have no meaning to any external consumer.

Returns:

a number corresponding to the enumeration of states as represented by the STATUS_*

setStatus

protected void setStatus(int nStatus)

Determine the enumerated state of the Status object. This value is intended for internal and debugging use only, and should have no meaning to any external consumer.

Parameters:

nStatus - a number corresponding to one of the enumeration represented by the STATUS_* constants

isValid

public boolean isValid()

Determine if the Status object is valid. A Status object can be discarded (no longer used), in which case it will not be valid.

Returns:

true iff the Status object is still valid

isAvailable

public boolean isAvailable()

Determine if the Status object is available. A Status object is available if it is valid and no thread is currently processing the entry for which this Status object exists.

Returns:

true iff the Status object is available

isProcessing

public boolean isProcessing()

Determine if the Status object represents an Entry that is currently being processed.

Returns:

true iff the entry represented by this Status object is being processed

isCommitting

public boolean isCommitting()

Determine if the Status object represents an Entry that has been processed and the results of that processing are being committed. The "committing" status implies that no other thread is allowed to do anything related to the entry that this Status represents.

Returns:

true iff the entry represented by this Status object is being committed

getOwnerThread

public java.lang.Thread getOwnerThread()

Determine the thread that owns the Status object, if the Status object is processing or committing.

Returns:

the owning thread, or null

setOwnerThread

protected void setOwnerThread(java.lang.Thread thread)

Specify the thread that owns the Status object. For internal use only.

Parameters:

thread - the owning thread, or null

isOwnedByCurrentThread

public boolean isOwnedByCurrentThread()

Determine if the current thread owns this Status object.

Returns:

true iff the current thread owns this Status object

isEntryInFront

public boolean isEntryInFront()

Determine if the entry for which this Status exists is present in the front map.

Returns:

true iff the entry is stored in the front map

setEntryInFront

public void setEntryInFront(boolean fEntryInFront)

Specify whether the entry for which this Status exists is present in the front map.

Parameters:

fEntryInFront - pass true if the entry is stored in the front map, false if not

isEntryInBack

public boolean isEntryInBack()

Determine if the entry for which this Status exists is present in the back map.

Returns:

true iff the entry is stored in the back map

setEntryInBack

public void setEntryInBack(boolean fEntryInBack)

Specify whether the entry for which this Status exists is present in the back map.

Parameters:

fEntryInBack - pass true if the entry is stored in the back map, false if not

isEntryExistent

public boolean isEntryExistent()

Determine if the entry for which this Status exists is present in the front map or the back map.

Returns:

true iff the entry is stored in either the front or the back map

isBackUpToDate

public boolean isBackUpToDate()

Determine if the entry for which this Status exists has the same value in the front Map as in the back Map.

Returns:

true iff the value exists in the back Map, and the value in the front Map is the same as the value in the back Map

setBackUpToDate

public void setBackUpToDate(boolean fUpToDate)

Specify that the value stored in the back Map is known to be up to date (not needing to be written to the back if evicted from the front).

takeEvent

Obtain the most recent event that has occurred against the Entry for which this Status exists. If both the front and the back Map have event listeners which register events with the Status object, then the event could be from either the front or the back Map. If events have occurred on both the front and back Maps, the event from the front Map will be returned and the event from the back Map will be discarded; this can be explained by the fact that the front Map overlays the back Map, and thus the back Map events can be safely ignored if a front Map event has occurred. (This is possible because the back Map content is not monitored strictly, but the front Map content is.)

Returns:

the cummulative event for the Entry represented by this Status object, or null if there were no events

getExpiry

public long getExpiry()

Determine the expiry for the entry represented by this Status.

Returns:

the expiry, or 0L if there is no expiry

setExpiry

public void setExpiry(long ldtExpires)

Specify the expiry for the entry represented by this Status.

Parameters:

ldtExpires - the expiry, or 0L if the entry should not expire

hasExpiry

public boolean hasExpiry()

Determine if this Status represents an entry that will automatically expire.

Returns:

true iff the Status is for an entry that will expire

isExpired

public boolean isExpired()

Determine if this Status represents an entry that will automatically expire.

closeProcessing

Finish the processing of the entry for which this Status exists and proceed to the commit phase. The act of closing processing collects any side-effects to the corresponding front Map Entry (either from this or other threads) as a single event.

Returns:

all events that have occurred on this or other threads for the front Map Entry represented by this Status object while this Status object was "processing", or null if there were no events

commitAndMaybeInvalidate

protected boolean commitAndMaybeInvalidate()

Finish the commit for the entry for which this Status exists. If there are any threads waiting on the entry for which this Status exists, one will be notified that the Status is now available. If the entry for which this Status object exists is contained in the front Map, then it will proceed to the available phase. Otherwise, the Status will be invalidated and discarded from the Status registry.

This is an internal method. It requires the caller to have first synchronized on the registry (Map) that contains the Status objects before calling this method (or otherwise synchronizing on this Status object). Failure to follow this rule will result in deadlock and/or exceptional conditions.

Returns:

true iff this Status object has invalidated itself

registerFrontEvent

Register a MapEvent that has been raised by the front Map against the same key for which this Status object exists. If an event has previously been registered, the previous and new event are merged into a single merged event that incorporates the data from both events.

For truly predictable behavior, this requires that the front Map implementation be synchronized during the raising of events, such that an event will only be raised from the front Map on one thread at a time. The event listener (for the overflow map) must then synchronize on this Status object (to verify that it is indeed valid before registering the event) and the register the event while holding that synchronization. If the registration returns a deferred indicator, then the

Parameters:

evt - the event that has occurred against an entry in the front Map with the same key which this Status object represents

Returns:

true iff the event processing has been deferred, implying that this Status object should be registered in a list of Status objects that have events that need to be handled

registerBackEvent

Register a MapEvent that has been raised by the back Map against the same key for which this Status object exists. If an event has previously been registered, the previous and new event are merged into a single merged event that incorporates the data from both events.

Parameters:

evt - the event that has occurred against an entry in the back Map with the same key which this Status object represents

Returns:

true iff the event processing has been deferred, implying that this Status object should be registered in a list of Status objects that have events that need to be handled

getState

protected int getState()

Determine the state of the Status object. This value is intended for internal and debugging use only, and should have no meaning to any external consumer.

Returns:

the bit-packed state of the Status object

setState

protected void setState(int nState)

Specify the state of the Status object. This value is intended for internal and debugging use only, and should have no meaning to any external consumer.

Parameters:

nState - the new bit-packed state for the Status object

extractState

protected int extractState(int nMask)

Extract a particular masked value from the state of the Status object.

Parameters:

nMask - the mask identifying the value

Returns:

the extracted value

updateState

protected void updateState(int nMask,
int nValue)

Update a particular masked value within the state of the Status object.

Parameters:

nMask - the mask of bits to store the value within

nValue - the value to store inside that mask

extractFlag

protected boolean extractFlag(int nMask)

Extract a particular masked flag from the state of the Status object.

Parameters:

nMask - the mask identifying the flag

Returns:

the extracted flag as a boolean

updateFlag

protected void updateFlag(int nMask,
boolean f)

Update a particular masked flag within the state of the Status object.